1. Field of the Invention
This invention relates to a device which may be inserted into blood vessels, body cavities, etc. for radiating selectable areas in the vessels or cavities, for therapeutic or other purposes. More particularly, the present invention relates to an expandable catheter for placing in direct contact with a selected area in a blood vessel, body cavity or the like, which allows both radial and longitudinal control of radiation dosage.
2. State of the Art
Catheters have long been used for threading into blood vessels or other body orifices for such purposes as delivering emboli to target locations, delivering therapeutic drugs to such locations, sensing conditions in the vessel or cavity by sensors inserted into the catheter, etc. Typically, a guide wire is first threaded into the vessel or cavity until the distal end of the guide wire reaches a target location, and then the catheter which is placed about the guide wire is moved to the target location as guided by the guide wire. Then, depending upon the treatment, the guide wire may be withdrawn or left in place and the treatment commenced, such as by injecting drugs through the catheter to the target location.
There are some diseases, such as restenosis, which become sited in blood vessels or body cavities which cannot be effectively treated by drugs, but instead respond to appropriate doses of radiation from a radioactive source. Effective treatment of such diseases requires exposure of diseased tissues to levels of radiation within a therapeutic range. This presents a problem if the diseased areas are not readily accessible but can only be reached by a pathway which extends past healthy tissue to the diseased area. It would thus be desirable to have an apparatus for selectively exposing areas of blood vessels, body cavities and the like to radiation from a radioactive source which may be threaded into a patient's anatomy such as by means of a catheter.
However, it is desirable to provide the radiation dose to the diseased area without exposing surrounding healthy tissue to such radiation. Thus, it is desirable to place the radiation source in as close a proximity to the diseased area as possible in order to produce a desired benefit, while also keeping the radiation source as far away from healthy tissue as possible. It would thus be desirable to provide an apparatus and method for selectively exposing areas of blood vessels, body cavities and the like to radiation in which healthy tissue in such vessels and cavities are protected from such radiation during insertion of the device and treatment therewith. It would thus also be desirable to have an apparatus for selectively exposing areas of blood vessels, body cavities and the like to radiation from a radioactive source wherein the radiation dose may be both radially and longitudinally controlled relative to the patient's anatomy.